GB1298338A - Improvements relating to shears for metal stock - Google Patents

Abstract

1298338 Shearing GKN MACHINERY Ltd 23 Jan 1970 [5 Feb 1969] 6152/69 Heading B3W [Also in Division H4] A reciprocatory shear 12, 13 for cropping metal stock 10 has one or more acoustic testing units, 14, 114, for detecting the extent of defective end portions to be cropped from the stock, each including at least one testing apparatus 22 and actuating means for passing an acoustic transmission block of the or each apparatus into operative engagement with the stock under a pressure sufficient to cause plastic deformation of the stock. As shown, the testing unit 14 constitutes a hold down for the stock. The or each apparatus 22 comprises a steel block (23), Fig. 3 (not shown), divided into portions (24) by a slot (25). A recess (26) in each portion houses an acoustic transducer (27) or (28), one of which is a transmitting device and the other a receiving device. Each portion includes a cooling chamber (31). The blocks are reciprocated by piston and cylinder units 20, 18. The hold down test unit 14 is supported by two posts 15 forming piston rods of compound cylinder units 16. In operation, hydraulic fluid is supplied to the upper chambers 39 of the lower cylinders 36 to move the unit 14 into engagement with the stock 10. Fluid is then supplied to the upper chambers 37 of the upper cylinders 35 which are in communication with the upper chambers 41 of the cylinders 18 so that additional thrust is applied to the unit 14 to oppose the thrust exerted on it by the piston and cylinder units 20, 18. Data from the test unit(s) is evaluated in a computer and the stock advanced an appropriate distance before cropping. A support plate 45 mounted on an hydraulic cylinder unit 46-48 is lowered to allow the cropped portion to fall away. On the discharge side of the shear pressure fluid is supplied to the upper chambers 158 of single cylinder units 156 to move the unit 114 into engagement with the stock 10. Whilst high pressure fluid is supplied to the upper chambers 141 of the cylinders 118 to drive the blocks into the stock, shut-off valves are closed in lines 162 and 163 so that the thrust exerted on the unit 114 by the cylinder units 120, 118 is transmitted to the shear frame 17 through the fluid in cylinders 156. A support plate 164a is pivoted between operative and inoperative positions by a further piston and cylinder unit (not shown). A laterally-acting unit (14b), Fig. 2 (not shown), similar to unit 114, may be provided on the feed and/or discharge side of the shear, acting against a vertically movable plate (165b). Such a unit on the discharge side may be used as a pusher for removing cropped lengths. Instead of using compound piston and cylinder units, an additional unit may be provided for producing additional thrust or a two-pressure system may be used.